Streamlined hinge line for aircraft



'l/II/I/ I ll/Ill A 4 Feb. 6, 1945. v R RNE 2,368,702

STREAMLINED HINGE LINE FOii AIRCRAFT Filed A ril a, 1943 2 Sheets-Sheet 1 WII/K/4HA\( //I//IA INVENTOR RAYMOND 0. 50mm:

Feb. 6, 1945. BQURNE 2,368,702

s'rnnmnmsn runs}: LINE FOR AIRc'RAF'r" Filed A z n a, 1943 2 Sheets-Sheet 2 J2 a: as Y 4 INVENTOR RAYMOND D. Baum:

ATTORNEY and theelevator.

Patented Feb. 6, 1945 UNITED s T PATENT OFFICE I 2,368,702 .s'mmmmep HINGE I-IINE FORAIRGRAFT Raymond -11. Baum, 'Mi'ddletown, Ohio ApplicationlApril s, 1943, Serial No. 482,239

' l'ClaLim. (c1.244--1s0') This invention relatestoaircraft, and particularly to the construction of the control surfaces of the aircraft. 1 v.

object of theinvention is to provide means to streamline the hinge line between a control surface and a stationary surface.

Another object of the invention is to provide means for eliminating the drag produced upon an aircraft that results from the angular position of a control surface relative to a stationary surface when the control surface is operated.

It is another object of the invention to provide meansfor preventing air that is passing over the wing or tail surface of an aircraft from entering the space between the main surface and a control surface of a wing or tail structure. i

It is another object of the invention to provide l tion' of an aircraft showing the invention applied to the hinge line of the control surfaces.

Fig. 3 is a transverse cross-sectionalview taken along line 3"3 of Fig. 1, showing a flexible membrane extending across the hinge line between the horizontal tail plane and the elevator ofthe tail assembly.

Fig.4 is a'transvers'e cross-sectional view similar to Big. 3', showing an elevator disposed angularly with respect to the horizontal tail plane to illustrate the streamline efiect obtained by the application of this invention.

Fig. 5 is a partial transverse cross -sectional view similar to Figs. B an d 4, in perspective, showing one of the methods for attaching a flexible membrane to the skin. of the horizontal tall plane and elevator of a tail assembly;

Fig. 6 is a transverse.cross-sectional view, in perspective, showing another method of attaching a flexible membrane between the tail plane Fig. 7 is a transverse cross-sectional view of a wing 'section'in" more detailed constructional arrangement showing, the invention applied thereto.

Fig. 8 is a transverse cross-sectional View of a wing section showing the invention as applied toa flat hinge.

Fig. 9 is a cross-sectional view of a modified arrangement of the closure member for a 'hinge that reduces the amount of flexible material used in the cover member. I

Figs. 10, l1 and 12 are further modified arrangements of the cover member for conserving the flexible material.

This invention relates to aircraft, and particularly to a means for closing the space between a main wing or tail surface and a control surface at the hinge'line thereof. When the ailerons, elevators, and rudder are assembled upon the wings, the horizontal tail planes and the vertical fin respectively of an aircraft, there is a space provided between, the stationary or main surface and the control surface. The hinged end of the control surfaces are rounded so that they can be moved to relatively step angles relative to the main wing or tail surface to produce rapid-maneuvering of the aircraft when thecontrol surfaces are operated. There is of necessity a certain amount of ,space provided between the main surface and the edge 'of the control surface to permit this angular movement of the "control surface relative to the main surface.

As long as the aircraft is-in normal horizontal flight the air flow across the wing or tail surface and control surfaces will be relatively smootn'thestreamline flow of air bridging the ap 'between the main surface and control surface in the *hinge line. Howeven'when a control surface is operated and it is positioned angularly to the main surface, the normal streamline flow of air across the main surface and the control surface is broken. Under such conditions the angularity produced between the main surface and the control surface creates'a turbulence in the air at the hinge line of the control surface. This turbulence or burbling of the air reduces the efficiency 'of the control surface, and also produces drag upon the aircraft.

"To overcome these difficulties, according to,

and is applied to an aircraft disclosed in this invention consisting of a fuselage I having a cockpit A suitable-power source is carried by the fuselage ID for driving the air screw l2. The wings |3 and M are'secured to the fuselage l6 and are provided with the usual ailerons l5 and I6, respectively.

The tail assembly for the fuselage l6 consists of the horizontal tail plane N that is provided with the elevators I8 and 19. The vertical fin of the tail assembly supports the rudder 2|.

Each of the control surfaces l5, I6, I8, l9 and 2| are supported upon a suitable hinge connection so that they can be disposed angularly with respect to the main surfaces adjacent the respective control surfaces. As illustrated in Fig. 3, which is a cross-section through the horizontal tail plane and elevators l8 and I9, respectively,

the elevator I8 is carried upon a hinge pin 22 that extends into engagement with the tail plane I1 so that the elevator l8 can be rotated upon the hinge pin 22 for positioning the same angularly with respect to the tail plane IT, as shown in Fig. 4. The forward end 23 of the elevator i8 is rounded so that the elevator can rotate upon the hinge pin 22 without causing interference with the rear wall 24 of the .cut-out portion 25 pro- I8 without producing any substantial turbulence at the hinge line of the elevator I8.

However, when the elevator I8 is operated to position it angularly with respect to the tail plane l, as shown in Fig. 4, the normal streamline flow of air between the tail plane I! and the elevator |8 is disturbed and the space, 26 produces a decided irregularity in the streamline flow 0f the air between the two surfaces. This is particularly true on the underside of the tail plane and elevator when the elevator is in the position shown in Fig. 4. The turbulence, or burbling of air produced at this hinge line at the space 26 reduces the eificiency of the elevator I6 and also produces drag upon the aircraft.

To eliminate this turbulence of air at the hinge line of the elevator l8 a flexible membrane is positioned across the space 26 provided at the hinge line between the elevator l8 and the tail plane IT. A similar flexible membrane 36a is I disposed across the hinge line on the opposite side of the tail plane and elevator to thereby form an enclosed space 26, which encloses the forward end 23 of the elevator l8.

This flexible membrane may be of any suitable flexible material, such as rubber, or a rubberlike material, such as the synthetic rubber products. When the elevator I8 is now positioned as from the skin of the tail plane to illustrate the the space 26 and reach the skin of the elevator surface.

face the membranes, as indicated by the memline of adhesive that secures the edge 28 to the skin of the tail-plane IT. The edge 28 of the membrane 30a is tapered to a feather edge so that when it is secured to the skin of the tail plane I! there will be substantially no surface elevation of the membrane 36a from the skin of the tail plane Suitable adhesives are provided for securing rubber and synthetic rubber products to surfaces of various types, and therefore the adhesive used will depend upon the material of the surface of the skinof the tail plane Also, the edge of the membrane 30a could be vulcanized to the skin of the tail plane ll by suitable vulcanizing processes now known to those skilled in the art for vulcanizing rubber and rubber-like products to metal surfaces. The trailing edge 29 of the membrane 36a is similarly attached to the elevator l8, also, the membrane 36 is attached to the tail plane and elevator in a like manner.

In Fig. 6 there is shown a slightly modified arrangement for attaching the flexible membranes to the tail plane I10, and the elevator l8a. In this arrangement a recess 3| is provided along the rear edge of the tail plane I1 and a similar recess 32 is provided along the forward edge of the elevator |8. A sheet of flexible material 36b is positioned across the space 26a at the hinge line of the elevator l8a and has the ends thereof disposed in the recesses 3| and 32. Metal strips 33 and 34 are placed upon the edges of the flexible sheet, or membrane 30b. Suitable bolts or rivets 35 extend through the metal strips 33 and 34, the edges of the membrane 36band the tail plane and elevator to secure the membrane 301) thereto. A similar flexible membrane 300 is disposed upon the opposite side of the hinge line 'of the elevator l8a.

While the description herein has been directed to the use of flexible membranes across the hinge line between the horizontal tail plane and the elevator of a tail assembly, yet it is to be understood that such flexible membranes can be placed across the hinge line of any control surface of the aircraft including the ailerons I5, l6, and the rudder 2|. The flexible membranes across the hinge line of the ailerons l5 and I6 are indicated by the reference numerals 36 and 37, respectively, while the flexible membrane across the hinge line of the rudder 2| is indicated by the numeral 38. Each of the membranes heretofore referred to are secured to the surfaces on opposite sides of the hinge lines so that a smooth streamline contour results at the hinge line when the control surface is moved relative to the main To produce a smooth streamline surbrane 30, see Fig. 4, are attached to the surfaces adjacent the hinge line at points that are relatively remote from the hinge line, whereby the flexible membrane may produce a smooth surface contour between the surfaces on opposite sides of the hinge line. It will be noted that the points I of attachment of the membrane 36 are relatively remote, being indicated by the numerals 39 and 40. It is to be understood, of course, that the flexible membranes are to have sufficient stiffness to prevent themfrom vibrating, and yet will not offer any substantial resistance to the operation of the control surfaces.

In Fig. 7 there is shown a more detailed construction of a wing structure that'incorporates the feature of the invention. In this structure there is provided a front spar 56 and a rear spar 5| that extend longitudinally along the wing disturb the air flow.

As shown in Fig. 7 the aileron 6!) is pivoted upon the pin or rod extending between suitable bearing members in the wing structure.

The membrane 62 that extends between the skin 51 of the wing and the skin 63 of the aileron may consist of a flexible portion 64 and a fabric portion 65 that is more clearly shown in Fig. 9. The rubber, or rubber like, section 64,'provides flexibility or stretchability, to themembrane 62 so that when the aileron 60 is moved relative to the wing structure that the membrane can stretch as required by the movement of the aileron.

As shown in Fig. 9 the fabric portion 65 is imbedded in the rubber portion 64 adjacent one surface thereof so that the surface of the fabric portion is substantially parallel to the surface ofv the flexible portion 64. This surface 66 is the one that is exposed to the air moving over the surface of the wing so that there will be no protrusions or irregularities in the wing surface that will The flexible portion 64 is provided with a feather edge 61 so that when the flexible portion 64 is secured to the surface of the wing there will be no protrusion of .the edge of the flexible portion that would disturb the air flow over the Wing surface. If desired the flexible portion may take the form disclosed in Fig. 10 wherein the portion 64a is feathered on both edges.

Also, in place of securing the flexible portion 64a to the Wing surface, the flexible portion can be positioned between two fabric portions 68 and 69 as illustrated in Fig. 11. In this manner the flexible portion 64b is provided as the central area of the membrane 62. It may be that in some instances it will be easier to secure or cement fabric portions to the surface of the wing than the flexible portion, in which instance this latter form would be preferable. Fig. 12 illustrates a manner in which the fabric portion 65 may be cemented to therubber portion 64 by disclosed. 1

means of adhesive 10 in place of vulcanizing the same within the body of the rubber strip.

In Fig. 8 there is shown a wing. structure 15.

similar to that disclosed in Fig. 7 except that a flap 16 is hinged to the wing. structure by the hinge pin 11. During normal flight operations the flap l6 lays against the under surface of the wing structure and forms apart of the streamline surface of the wing. However, the hinge connection for the flap 16 offers an obstruction to the streamline airflow across the wing surface because of the openings required for the hinge of the flap, these openings producing a disturbance in the air flow. To overcome this disturbance in the air flow a flexible membrane 18 is provided across the hinge joint from the under surface of the wing I5 to the under surface of the flap 16. The flexible member or membrane 18 can be any of the forms heretofore While the apparatus disclosed and described herein constitutes a preferred form of the invention, yet it is to be understood that the particular apparatus can be modified without departing from the spirit of 'the'invention and that all such modifications as fall within the scope of the appended claim are intended to bev included herein.

Having thus fully described my invention what I claim as new and desire to secure by Letters Patent is:

An aircraft that includes in combination, a main supporting surface, a control surface movable angularly to the supporting surface upon a hinge line, recess means in said. main surface and said control surface extending longitudinally along the hinge line therebetween that is feathered along the side thereof most remote from said hinge line, and a flexible membrane extending across said hinge line in engagement with said surface to close the space produced at said hinge line and have opposite longitudinal edges thereof feathered for positioning in said recesses in said surfaces with the feathered edges of said recesses for producing a streamlined contour between said surfaces and across said hinge line, said feathered edges of said flexible membrane receiving a fabric strip extending longitudinally along the same and co-extensive therewith for securing said flexible membrane to said surfaces.

RAYMOND D. BOURNE. 

